Photosynthesis is of fundamental importance as a biological process and it is important to understand its mechanism, and control by factors within the plant and in the environment. Plants take up carbon dioxide from the atmosphere and assimilate it into organic phosphates which are used for synthesizing starch, sucrose, amino acids, etc. A limited number of higher plants, including maize (corn), have evolved a mechanism for concentrating carbon dioxide in their leaves so that the low concentration in the air (0.034%) does not limit their ability to perform photosynthesis. This mechanism involves a biochemical pathway called the C.4 cycle, and such plants are called C.4 plants. C..4 plants achieve very high rates of photosynthesis under high temperature and light intensities. However, in many C.4 plants, photosynthesis is quite sensitive to moderately low temperatures (i.e. 10 to 15.oC while a few species or races are more tolerant. In this project, sensitivity to low temperature will be examined relative to processes associated with the C.4 cycle (transport of organic compounds and function of proteins as catalysts of reactions). Factors which protect the processes under low temperatures will be examined in C.4 plants which are chilling tolerant. Basic knowledge gained from these studies will be of value in exploiting the mechanism of C.4 photosythesis so that it can be used on a larger scale in production of food, biomass and in urban applications.
